Question

For the isoelectronic series \(S^{2-}, Cl^{-}, Ar, K^{+}\) and \(v\), which species requires the least energy to remove an outer electron?

• A. \(S^{2-}\)
• B. \(Cl^{-}\)
• C. Ar
• D. \(K^{+}\)

Hint:

In isoelectronic species, the species with the most negative charge or least nuclear charge is easiest to ionize.

Answer 1

The Correct Option is A

In the isoelectronic series, the species with the least nuclear charge (lowest effective nuclear charge) will require the least energy to remove an electron. Since \(S^{2-}\) has the most electrons and the smallest nuclear charge, it will require the least energy to remove an outer electron. Thus, the correct answer is (a) \(S^{2-}\).